Add persistent sketch-constraint system (ocs_gcs port) and named-parameters handoff docs

Ports FreeCAD's planegcs 2D geometric constraint solver to Rust as a new
crates/ocs_gcs workspace member, and wires it into the document/scene model
as a persistent SketchConstraintSet: Coincident, Horizontal/Vertical,
Parallel/Perpendicular, Equal, Tangent, Distance, Angle and Radius
constraints that re-solve live (including mid-drag, not just on release),
render glyphs and a DOF badge, flag conflicts with a one-click resolver
pill, and round-trip through save/load via an XRecord blob.

Also includes docs/command_reference.md (a statically generated reference
of every registered command and its prompt sequence) and
docs/named_parameters_design.md + docs/backlog.md, which hand off the next
queued feature (a named-parameter/expression table) and consolidate every
deliberate scope-down and open gap found along the way, so a fresh session
has a complete starting point.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

packaging/Info.plist

@@ -5,7 +5,7 @@
     <key>CFBundleDevelopmentRegion</key>
     <string>en</string>
     <key>CFBundleDisplayName</key>
-    <string>Open CAD Studio</string>
+    <string>OCS-__BUILD_STAMP__</string>
     <key>CFBundleExecutable</key>
     <string>OpenCADStudio</string>
     <key>CFBundleIconFile</key>
@@ -15,7 +15,7 @@
     <key>CFBundleInfoDictionaryVersion</key>
     <string>6.0</string>
     <key>CFBundleName</key>
-    <string>Open CAD Studio</string>
+    <string>OCS-__BUILD_STAMP__</string>
     <key>CFBundlePackageType</key>
     <string>APPL</string>
     <key>CFBundleShortVersionString</key>